Mazda Eunos Cosmo 20B
JDM Reference • 1990–1996
JC
20B-REW
276 hp / 280 PS
~3,549 lb
4-Speed Automatic
RWD
Three-Rotor
Mazda Eunos Cosmo 20B Quick Specs
| Horsepower | 280 PS / 276 hp @ 6,500 rpm |
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| Torque | 402 Nm / 296 lb-ft @ 3,000 rpm |
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| Curb Weight | Approx. 1,610 kg / 3,549 lb, depending on version |
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| Engine | 20B-REW 3-rotor sequential twin-turbo rotary |
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| Transmission | 4-speed automatic |
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| Drivetrain | Rear-wheel drive |
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| Model Years | 1990–1996 in the Japanese market |
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| Body Style | 2-door luxury grand touring coupe |
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The Eunos Cosmo was also offered with two-rotor rotary engines. This database index entries and technical values refer specifically to the JC-series 20B three-rotor version.
Core Specifications
| Model | Mazda Eunos Cosmo 20B |
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| Chassis / Platform Reference | JC |
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| Market | Japan / Japanese Domestic Market (JDM) |
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| Model Years | 1990–1996 |
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| Body Style | 2-door luxury coupe |
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| Layout | Front-engine, rear-wheel drive |
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| Transmission | 4-speed automatic |
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| Engine | 20B-REW three-rotor rotary |
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| Drivetrain | Rear-wheel drive |
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| Curb Weight | Approximately 1,610 kg / 3,549 lb, depending on source and equipment spec |
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| Fuel Requirement | Premium unleaded gasoline |
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Engine Specifications
| Engine Code | 20B-REW |
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| Configuration | Three-rotor rotary |
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| Displacement | 1,962 cc (using Mazda rotary engine displacement convention) |
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| Aspiration | Sequential twin-turbocharged |
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| Valvetrain | Rotary ports (no reciprocating valves) |
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| Block / Head | Cast iron rotors/housings, aluminum intermediate plates |
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| Fuel System | Electronic fuel injection |
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| Horsepower | 280 PS / 276 hp @ 6,500 rpm |
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| Torque | 402 Nm / 296 lb-ft @ 3,000 rpm |
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| Redline | 7,000 rpm |
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Dimensions & Chassis
| Wheelbase | 2,750 mm / 108.3 in |
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| Length | 4,815 mm / 189.6 in |
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| Width | 1,795 mm / 70.7 in |
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| Height | 1,305 mm / 51.4 in |
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| Front Suspension | Independent suspension setup |
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| Rear Suspension | Independent multi-shock luxury setup |
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| Brakes | Four-wheel ventilated disc brakes |
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Model-Year Notes
1990
- Launch of the JC-series Eunos Cosmo in the Japanese luxury market.
- Introduced the flagship 20B-REW variant as the world’s first production triple-rotor sequential twin-turbo vehicle.
- Positioned exclusively through Mazda’s premium Eunos sales channel.
1991–1995
- Production continued in limited numbers as an exclusive high-specification grand touring personal luxury platform.
- Maintained standard 4-speed electronic automatic transmission mated to the high-torque 20B engine.
1996
- Final production year for the JC platform Eunos Cosmo.
- The 20B-REW family remains unique to this platform as Mazda’s sole production three-rotor vehicle family line.
Factory Colors
Classic Black / Dark Shades
Color availability varies by production run and factory option packaging. JDM luxury grand tourers regularly featured conservative premium exterior paints combined with upscale leather cabins.
Interesting Details
Three-Rotor Production
The 20B-REW used three rotors rather than the ubiquitous two-rotor layout. It remains the only production three-rotor engine ever sold to the public in a road-going automobile.
Grand Tourer Philosophy
The Cosmo 20B was explicitly not a sparse performance model. Its body scale, premium electronics, automatic-only drivetrain, and heavy insulation targeted high-end luxury personal coupe sectors.
Common Search Questions
| How much horsepower does the Mazda Eunos Cosmo 20B have? |
The factory 20B-REW engine produces 280 PS / 276 hp at 6,500 rpm, conforming to the period’s Japanese gentleman’s agreement limit. |
| How much torque does the Eunos Cosmo 20B make? |
It develops 402 Nm / 296 lb-ft of torque at a very low 3,000 rpm, aided by its sequential twin turbochargers. |
| What is the displacement of a 20B rotary engine? |
The 20B has a calculated physical displacement of 1,962 cc according to standard Mazda rotary displacement metrics. |
| Did the Eunos Cosmo 20B come with a manual transmission? |
No, all factory 20B-REW triple-rotor models were equipped exclusively with a high-torque 4-speed automatic transmission. |
| What is the chassis code for the triple-rotor Cosmo? |
The vehicle belongs to the JC chassis generation, manufactured between 1990 and 1996. |
Related Models
| Mazda RX-7 (FD) |
Two-rotor twin-turbo sports car built during the same era. The FD chassis prioritized pure lightweight performance over the Cosmo’s luxury grand touring target.
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| Eunos Cosmo 13B |
The sister variant within the JC platform powered by the smaller twin-rotor 13B-REW rotary engine configuration.
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Comparable Cars
| Toyota Soarer (Z30) |
Premium rear-wheel-drive Japanese luxury touring coupe holding parallel market placement, using high-output inline six or V8 piston engines rather than rotaries.
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| Nissan Leopard |
Japanese-market luxury grand touring vehicle line emphasizing front-engine, rear-wheel-drive packaging and high-end cabin amenities.
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| Mitsubishi GTO / 3000GT |
Heavy, technology-laden Japanese performance coupe utilizing a twin-turbo V6 engine array and advanced mechanics.
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Buying & Ownership Evaluation Notes
The Eunos Cosmo 20B is a highly specialized Japanese domestic market vehicle. Evaluation prior to acquisition should rigorously isolate rotor housing compression values, sequential turbo actuator health, cooling stack capabilities, automatic gearbox fluid states, and custom electrical diagnostic functions.
Replacement component infrastructure is tightly constrained. Routine ignition elements share general rotary support networks, but custom 20B blocks, structural body trim panels, active luxury instrumentation clusters, and interior parts demand careful planning independent of typical Mazda parts supplies.
MSC Taxonomy
| Make | Mazda / Eunos |
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| Model | Cosmo 20B |
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| Chassis Code | JC |
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| Era | 1990s |
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| Layout | Front-engine |
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| Drivetrain | Rear-wheel drive |
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| Induction | Sequential Twin-Turbocharged |
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| Engine Configuration | Three-Rotor Rotary |
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| Transmission | 4-speed automatic |
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| Body Style | Luxury Coupe |
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| Market | Japan (JDM) |
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| Country Of Origin | Japan |
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| MSC Category | Rotary Grand Touring Coupe |
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Summary
The Mazda Eunos Cosmo 20B is a Japanese-market JC-series luxury coupe powered by the 20B-REW three-rotor sequential twin-turbo rotary engine. It combined a front-engine, rear-wheel-drive layout with a four-speed automatic transmission and premium coupe positioning, firmly separating it from dedicated sports cars like the RX-7 or RX-8 lines.